An exemplary embodiment presented herein relates to a multi-beam optical range sensor and, for example, to a multi-beam optical range sensor for detecting a direction and a distance of a measuring object, which is to be measured, by detecting whether or not the measuring object is present within a certain range.
Conventionally, a multi-beam optical range sensor, as shown in FIGS. 7A to 7C, includes a plurality of light-emitting elements 114, and light-emission side lenses 115 equal in number to the plurality of light-emitting elements 114 (see JP H09-203631 A).
Light outputted from the light-emitting elements 114, passing via the light-emission side lenses 115, is reflected by a detection object, and the resulting reflected light is condensed by a light-reception side lens 116, forming a spot on a light-receiving element 117 serving as a position-detecting element. It is noted here that the light-reception side lens 116 comprises one toroidal lens and the light-receiving element 117 comprises also one element.
Therefore, while the plurality of light-emitting elements 114 are made to emit light one by one with the timing shifted for each, output signals of the light-receiving element 117 are read in synchronization with the timing of light emission of each light-emitting element 114, so that a direction of the detection object as well as a distance to the detection object can be detected by an output signal obtained from the light-receiving element 117 responsive to the timing of the light emission of each light-emitting element 114.
For this prior-art multi-beam optical range sensor, which includes a plurality of light-emitting elements 114 and a plurality of light-emission side lenses 115, there has been a need for allowing a larger space for the light emission side. As a result of this, the sensor would be large in scale as a whole.
Besides, since the plurality of light-emitting elements 114 are made to emit light one by one with the timing delayed and the signal of the light-receiving element 117 on the light reception side is read in synchronization with the timing, the light-emitting elements 114 need to be made to emit light all in order in order to detect detection objects present over a wide range, taking longer time to detect the direction and distance of a detection object.
Also in the prior art example, each beam emitted in its specified direction is scanned. In this case, when a person attempts to add a scan of the emitted beam in another direction in order to, for example, detect in a perpendicular direction to the above scanning direction, there is a need for adding the light-emitting elements and the light-emission side lenses each in the same number as those of the foregoing, and further adding the light-receiving element 117 on the reception side as well as the light-reception side lens 116. As a result of this, the sensor would become bigger in scale as a whole, hence no longer practical.